Advisor: Ragnar Björnsson and Egill Skúlason, Professor at the Faculty of Physical Sciences.

Examiner: Tobias Krämer, Lecturer at Maynooth University, Ireland

Abstract

Nitrogen fixation, the reduction of dinitrogen (N2) to ammonia (NH3), is essential for life. Nature reduces dinitrogen via a group of enzymes, called nitrogenases, found in a group of microorganisms known as diazotrophs. The Azotobacter vinelandii molybdenum nitrogenase is the most studied nitrogenase but very little is known about the nature of the redox states of nitrogenase and its mechanistic details, e.g., the binding of dinitrogen, hydrogen evolving sites, etc. This project’s aim was to elucidate, using computational chemistry methods, how the catalytic iron-molybdenum cofactor (FeMoco) reduces dinitrogen and other substrates. In this research I discuss my investigation of bioinspired synthetic [MoFe3S4] cubanes and their similarities to FeMoco, focusing on their catalytic reaction mechanisms for substrates also catalysed by nitrogenase. Leaving the synthetic world, we modelled reduced states of the cofactor and we discuss the probable underlying mechanisms behind substrate binding and reduction.